1. Field of the Invention
The present invention relates to an image processing apparatus suitably applied to a page printer, a digital copying machine, and the like.
2. Related Background Art
Conventionally, most page printers do not have a function of generating a large image. In addition, a storage means for image generation has a capacity corresponding to only one page of the maximum outputtable image size. Even when the image size can be changed, since the maximum outputtable image size is relatively small, such a page printer is used for outputting an image in the maximum image size or in a size close to it.
However, when the page printer has only a storage capacity corresponding to one page of an image, image development processing for the next page cannot be started until an image output operation for the current page is completed. For this reason, in a compound machine comprising a copying machine and a page printer having a high print speed, the high print speed cannot often be sufficiently utilized. Most of such compound machines have a relatively large maximum outputtable image size. Meanwhile, image sizes that a user frequently outputs are often half or less of the maximum image size. In this case, the use efficiency of a memory is low.
A conventional image forming apparatus such as a page printer having a recording unit executes recording using a density obtained by expressing the density of one pixel as a binary value. For this reason, when the resolution of image data to be recorded is different from that of the recording unit, the resolution of the recording unit must be changed by the image forming apparatus side to match with that of the image data, or resolution conversion processing of binary data must be performed.
As for image data whose resolution can be changed, e.g., image data such as vector data, binary image data to be developed is determined by the resolution of the recording unit. In the image forming apparatus, image data is developed to binary image data in correspondence with the resolution of the recording unit, and the developed data is output from the recording unit.
However, as a countermeasure to be taken when the resolution of the input image data is different from that of the recording unit of the image forming apparatus, to prepare a plurality of resolutions in the recording unit of the image recording apparatus results in a complicated apparatus arrangement and high cost, and only the prepared resolutions can be used. When resolution conversion of binary image data is performed in the image forming apparatus, image quality is considerably deteriorated.
Furthermore, when vector data or the like is developed to binary image data, if the resolution of the recording unit is high, it takes much time in the image forming apparatus to develop image data.